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Classroom Ready

The Classroom Ready graphical icon is used by NSDL with selected resources in the library to indicate the resource may have greater utility for teaching and learning. This may be demonstrated in a variety of ways: by adhering to curriculum or professional development goals of users; by demonstrating capacity for encouraging critical thinking, problem solving, interdisciplinarity, collaboration, or interactivity (21st century skills), or by its capability to be embedded in or disseminated by learning applications or platforms (see Learning Application Readiness, or LAR).


Similar to museum and library collections, NSDL collections are organized arrangements of items. An NSDL collection may have been submitted by a person or organization, or the collection may be gathered automatically by NSDL. For example, resources that have been suggested via the Recommend a Resource form are assigned to NSDL general subject area collections - see Browse Collections.

Collection Record

A record that describes the entirety of a collection using subject descriptors that pertain to the collection as a whole. Descriptive information is normally drawn from the collection's website, or About pages, or may be contributed by the provider themselves.


Collection Workflow Integration System. An open source software system to assemble, organize, and share collections of data about resources, conforming to international and academic standards for metadata. CWIS is developed and administered by the Internet Scout Research Group at the University of Wisconsin.

Digital Discovery System (DDS)

NSDL's search and discovery system (see NSDL Documentation Wiki).

Dublin Core (DC)

A simple set of metadata elements used in digital libraries, primarily to describe digital objects for collections management, and for exchange of metadata. The metadata standard used in the core library.


An item is a unit of a collection. It may be large or small, and it may itself contain parts or smaller units. Every item in NSDL is part of a collection. Typically, items are web pages, but they can also be images, video, datasets, and computer programs.

Item Record

Describes a particular resource or unit of a collection. May itself contain parts or smaller units. Every item in NSDL is part of a collection. Typically, items are web pages, but they can also be images, video, datasets, or computer programs.

Learning Application

Examples include the NSDL Science Literacy Maps; content managment systems (CMS), or learning management systems (LMS), such as Moodle, where an application uses a framework that characterizes resources by subject, education level, resource type, audience, and/or educational standards (educational metadata).

Learning Application Readiness, or LAR

A rigorous educational metadata format developed and utilized by NSDL and some partners for improving the quality of resources and metadata in the National Science Digital Library. LAR refers to how closely educational resources, collections, and their related metadata are aligned to educational goals, curriculum, or professional development needs of users, and how readily those resources and collections can be embedded in tools and services that educators and learners use.

Library scope

Resources provided via primarily support the K16 education continuum (K12 to undergraduate), though the library also provides access to high quality collections supporting graduate education, and lifelong learning. NSDL LAR resources (collections characterized by metadata in the LAR format) are designed to initially serve the K12 education sector, because they are aligned to Common Core Mathematics education standards (and ultimately Next Generation Science Standards).


IEEE Learning Object Metadata, a metadata framework for describing digital resources.


The Learning Resource Metadata Initiative to promote use and implementation of a common metadata standard supporting end-user search and discovery of educational resources, building on work originated by Led by the Association of Education Publishers (AEP) and Creative Commons; funded by the Bill & Melinda Gates Foundation and the Williams and Flora Hewlett Foundation.


A Java-based, open source, full-featured search engine; utilized by NSDL.


MAchine-Readable Cataloging. One of the supported NSDL metadata standards. A data format developed by the Library of Congress that provides the mechanism by which computers exchange, use and interpret bibliographic information and its data elements make up the foundation of most library catalogs used today.


Structured or standardized information used to describe digital and physical resources, (e.g. title, author, subject, text or multimedia format), that aid in searching for and understanding resources. Often defined as "data about data".

Metadata Framework

A recommended or required set of standardized metadata terms in XML that characterize digital objects (resources) for interoperable exchange of metadata between entities. NSDL offers four metadata formats:

  • nsdl_dc – qualified (containing element refinements and encoding schemes) Dublin Core metadata framework used in NSDL. Features NSDL-specific controlled vocabularies for the following elements: Education Level, Audience, Type, and Access Rights. The most important elements in the NSDL_DC schema are: title, identifier (URL/URI), description, subject (and/or keywords), education level, and type. 
  • LAR – Learning Application Ready metadata framework that enables programmatic exchange of a rigorous set of required metadata fields characterizing high quality digital resources. The required metadata format for programmatic exchange of metadata with downstream user applications.
  • comm_para framework – enables the characterization of usage data about a resource (e.g. downloaded, favorited, rated, etc.). Allows usage data to be designated by audience, subject, or education level.
  • comm_anno framework – enables capture of user comments, reviews, and teaching tips; may also contain standards alignment information; allows annotations to include information about the record contributor, annotator, audience, subject, or education level.

Metadata Record

The record of the metadata (information) for a resource. Similar to the card in a card catalog system. This information is used by the search engine to find results for a search query.


NSDL ‘normalizes’ some metadata fields for consistency across all collections. For example, the education level field may contain the values of ‘4th grade’, ‘Fourth Grade’, ‘Elementary 4’. NSDL changes these values to be ‘Grade 4’ – which provides consistency for searching, reading, and consuming NSDL metadata in user interfaces and downstream services (i.e., platform providers that collaborate with NSDL to use NSDL metadata in serving their own educational audiences. An example is CTE Online).

In NSDL’s Search results, the display of information about a single resource may aggregate metadata from multiple providers, for the most comprehensive view of information, where more than one provider has cataloged and contributed metadata about the same resource.


National Science Digital Library. A free online library which directs users to exemplary resources for science, technology, engineering, and mathematics (STEM) education and research.


The canonical metadata format in the NSDL, develeped early in NSDL's history, over a decade ago. Transitioning by NSDL collection providers to use of the current preferred LAR metadata format is ongoing.

NSDL Collection System (NCS)

A cataloging and collection management system developed by NSDL and available for use by collection providers to manage and contribute their metadata to NSDL. 

NSDL Repository

The repository of educational resources, annotations, and paradata (use data), and a collection of collection metadata (metadata about collections) built on the Digital Discovery System (DDS) repository search server.


National Science Foundation. An independent federal agency created by Congress in 1950 that promotes scientific progress and provides funding to federally supported basic research groups conducted by America\'s colleges and universities in the fields of mathematics, technology and science.


Open Archives Initiative. The goal of the Open Archives Initiative Protocol for Metadata Harvesting is to supply and promote an application-independent interoperability framework that can be used by a variety of communities who are engaged in publishing content on the Web. Within NSDL, projects with standard metadata can expose their metadata for OAI harvesting by the NSDL on a regular schedule.

Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH)

A standard method and protocol by which metadata is transferred/exchanged, with NSDL. Metadata provided must pass in terms of OAI validation (a provider's OAI repository correctly implements OAI-PMH), and XML schema validation (meets the requirements of a designated XML schema).


Usage data about how users interact with a digital resource. Paradata in NSDL is received via use of the comm_para or comm_anno metadata frameworks (see metadata frameworks). Provision of collections of paradata is encouraged from all collection providers, and may take the form of integer-based (countable) metrics about resource use that providers are already collecting from their own websites and user communities, or may consist of user comments about resources that are provided as an annotation collection. Paradata is displayed in NSDL Search results (when available) as Usage Data, and in the full record about a digital resource, under the section heading Using this resource.


A designation used to refer to core provider partners of NSDL whose projects were supported by a specific funding track of the National Science Foundation's National STEM Digital Learning program, between 2004-2011. These core NSDL partners continue to collaborate with NSDL and to provide key disciplinary or audience-focused collections, and manage and operate their own educational portals.

Production Network

NSDL’s effort (2012-2013) to foster a sustainable business model of services provision as a network of partners both providing and consuming Common Core standards-aligned, learning-application-ready (LAR) K12 resource collections, annotated with usage data. While the initial focus of the production network is K12, overall NSDL library scope remains K16 and beyond. Resources discovered via continue to serve all educational levels.


Representational State Transfer. A web services architecture for networked systems that conforms to the W3C Web Architecture, and utilizes the semantics of Web standards, such as HTTP, URL, XML, HTML, etc. whenever possible.

Science Literacy Maps (SLM)

NSDL's tool for teachers and students to find resource relating to science and math concepts, based on AAAS' Project 2061 Benchmarks for Science Literacy. The SLM is based on NSDL's Strand Map Service, providing a customizable interactive graphical browsing interface to depict relationships between science and math concepts.


Simple Object Access Protocol. A lightweight protocol intended for exchanging structured information in a decentralized, distributed environment. It uses XML technologies to define an extensible messaging framework providing a message construct that can be exchanged over a variety of underlying protocols.


Science, technology, engineering, and mathematics.

STEM Exchange

The designation for a 2009-2012 initiative of NSDL focused on development of an expert network of education, research, technology, and policy partners engaged in improving STEM education. The effort emphasized pooling of expertise in digital resource creation and management to effectively characterize, customize, and adapt digital resources to the needs of multidisciplinary education communities; and to programmatically exchange data and services to STEM audiences within the workflows and platforms they use.

University Corporation for Atmospheric Research (UCAR)

The management entity for the National Center for Atmospheric Research (NCAR) and UCAR Community Programs (UCP)—the institutional home of the National Science Digital Library (NSDL).

Vitality Reports

Regular bi-monthly report provided to collection contributors that reports on the vitality, or health, of their resource URLs provided to NSDL. Also contains information on any weeding of resources in their collections conducted by NSDL.


A process of collection curation that removes low-quality or out-of-scope library resources or metadata in NSDL, such as resources or collections that have no contact person available for remediation of poor metadata quality.


Web Services Definition Language. An XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information.


eXtensible Markup Language, schema used by OAI for metadata harvesting.